Anisotropic bonded magnet having a composite structure and a method of making the same

Abstract

This invention discloses an anisotropic bonded magnet with a composite structure. The anisotropic bonded magnet is a composite magnet formed by nesting different types of anisotropic magnetic powder compacts or a multilayer magnet formed by alternating layers of different types of anisotropic magnetic powder compacts. This invention effectively improves the magnetic property distribution and significantly enhances the magnetic properties of the magnet. The preparation method of this invention is applicable to various bonded magnet material systems, exhibiting good versatility and engineering feasibility.

Description

Technical Field

[0001] This invention belongs to the field of magnetic functional materials technology. More specifically, this invention relates to an anisotropic bonded magnet with a composite structure and its preparation method. Background Technology

[0002] Bonded magnets possess advantages such as good performance consistency, precise dimensions, complex shapes, high material utilization, and easy integration with metal / plastic parts, holding an important position in the field of rare-earth permanent magnets. Among them, anisotropic injection-molded magnets exhibit superior magnetic properties: remanence ( Br ) and maximum magnetic energy product (( BH ) max The performance is significantly higher than that of isotropic injection-molded magnets. This invention modifies the pressing method, first pressing anisotropic magnetic powders such as NdFeB, SmCo, SmFeN, and MnBi into compacts, and then arranging them according to a specified pattern before preparing anisotropic bonded magnets with composite structures through cold pressing, warm pressing, or isostatic pressing. Traditional magnetic powder mixing processes for anisotropic bonded magnets have the following shortcomings: Poor mixing uniformity: The two types of magnetic powders have significant differences in particle size distribution and morphology, which easily leads to unevenness during the mixing process.

[0003] Magnetic properties cannot be fully utilized: It is difficult to achieve the optimal orientation of two types of magnetic powder under the same orientation conditions.

[0004] Poor process repeatability: Traditional single mixing methods make it difficult to achieve controllable distribution of magnetic powder in the thickness direction or space.

[0005] Changing the preparation method is an important issue in the study of high magnetic properties and high temperature resistant bonded magnets. Summary of the Invention

[0006] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0007] To achieve these objectives and other advantages according to the invention, the invention provides an anisotropic bonded magnet with a composite structure, wherein the anisotropic bonded magnet is a composite structure magnet in which different types of anisotropic magnetic powder are nested after pressing, or a multilayer structure magnet in which different types of anisotropic magnetic powder are alternately arranged between or within layers after pressing.

[0008] Preferably, the anisotropic magnetic powder includes at least two of NdFeB, SmFeN, SmCo, and MnBi.

[0009] A method for preparing anisotropic bonded magnets with a composite structure includes: mixing different types of anisotropic magnetic powders with acetone, coupling agent and binder to obtain different types of mixed magnetic powders; then pressing the mixed magnetic powders into blanks of different sizes under an orientation magnetic field and demagnetizing them; then pressing the blanks in a nested arrangement to obtain nested anisotropic bonded magnets; wherein the orientation method is to apply a continuous orientation magnetic field of 1.5~3.0T to the anisotropic magnetic powders through an orientation coil set outside the mold, and the orientation magnetic field duration is 1~100s.

[0010] Preferably, the anisotropic magnetic powder includes NdFeB and SmFeN, and the nested composite structure magnet is a composite magnet structure in which one magnet is nested inside another magnet.

[0011] Preferably, the coupling agent is KH570, the binder is bisphenol A type epoxy resin E51; the binder accounts for 2% to 4% of the mass of the mixed magnetic powder, the coupling agent accounts for 1‰ to 5‰ of the mass of the mixed magnetic powder, and the acetone accounts for 2% to 10% of the mass of the mixed magnetic powder.

[0012] Preferably, the pressure of pressing the mixed magnetic powder into a compact is 2~10 tons / cm². 2 The pressing time is 10~50s; the pressing method for anisotropic bonded magnets includes cold pressing, warm pressing or isostatic pressing, with a pressure of 6~60 tons / cm³. 2 The compression time is 10~100s.

[0013] A method for preparing an anisotropic bonded magnet with a composite structure includes: mixing different types of anisotropic magnetic powder with acetone, coupling agent and binder to obtain different types of mixed magnetic powder, pressing them under an orientation magnetic field to obtain a compact, and finally arranging and pressing the different compacts to obtain a multilayer anisotropic bonded magnet; wherein, the orientation method is to apply a continuous orientation magnetic field of 1.5~3.0T to the anisotropic magnetic powder for a duration of 1~100s.

[0014] Preferably, the multilayer magnet is a multilayer magnet in which one type of magnet and another type of magnet are arranged alternately between or within layers.

[0015] Preferably, the coupling agent is KH570, the binder is bisphenol A type epoxy resin E51; the binder accounts for 2% to 4% of the mass of the mixed magnetic powder, the coupling agent accounts for 1‰ to 5‰ of the mass of the mixed magnetic powder, and the acetone accounts for 2% to 10% of the mass of the mixed magnetic powder.

[0016] Preferably, the pressure of pressing the mixed magnetic powder into a compact is 2~10 tons / cm². 2The pressing time is 10~50s; the pressing method for anisotropic bonded magnets includes cold pressing, warm pressing or isostatic pressing, with a pressure of 6~60 tons / cm³. 2 The compression time is 10~100s.

[0017] To further improve the magnetic properties of anisotropic bonded magnets with composite structures, the binder is replaced with an equal amount of modified epoxy resin. The preparation method of the modified epoxy resin includes: Under nitrogen protection, bisphenol A type epoxy resin E-20, 5-carboxybenzotriazole (CBTA), and xylene were added to a reaction vessel and heated to 60-80℃ with stirring to dissolve. Triethylamine was added as a catalyst, and the temperature was raised to 110-120℃ and maintained for 4-6 hours. After the epoxy value of the system was monitored to be stable, the solvent and small molecule impurities were removed by vacuum distillation to obtain 5-carboxybenzotriazole graft-modified bisphenol A type epoxy resin E-20. The amounts of each raw material, by weight, are as follows: 80-100 parts of bisphenol A type epoxy resin E-20, 5-12 parts of 5-carboxybenzotriazole (CBTA), 0.2-0.5 parts of triethylamine, and 10-30 parts of xylene.

[0018] The present invention has at least the following beneficial effects: The anisotropic bonded magnet product with composite structure prepared by this invention has high stability, and the magnetic powder is uniformly distributed in its respective functional layers, which significantly improves the stability of the magnet's magnetic properties and structural performance.

[0019] This invention significantly enhances the overall performance of magnets, such as high temperature resistance, and improves the applicability of magnets' magnetic properties in special application environments by setting special functional layers.

[0020] The number, thickness and arrangement of layers in anisotropic bonded magnets with composite structures are controllable, which facilitates the adjustment of magnet performance and large-scale preparation, and has strong process adaptability.

[0021] This invention grafts 5-carboxybenzotriazole (CBTA) onto the molecular chain of bisphenol A type epoxy resin E-20 through a chemical reaction: under the catalysis of triethylamine, the carboxyl groups of CBTA undergo a ring-opening grafting reaction with the epoxy groups of the epoxy resin, resulting in a large number of benzotriazole functional groups covalently bonded to the epoxy resin molecular chain, rather than physical blending. This avoids the problem of corrosion inhibitor migration and precipitation in the resin matrix within the magnet, and achieves the integration of functional groups with the resin matrix.

[0022] By grafting benzotriazole groups, passivation protection was achieved on the magnetic powder, significantly inhibiting its oxidative degradation during high-temperature aging. This reduced the decrease in coercivity and irreversible domain flipping caused by oxidation, thereby significantly reducing magnetic flux loss. The CBTA-modified bisphenol A epoxy resin E-20 exhibited a significantly increased glass transition temperature, maintaining a stable glassy state even at 120℃. The degree of thermal degradation and aging shrinkage was greatly reduced, allowing it to maintain long-term encapsulation and adhesion of the magnetic powder, preventing magnetic performance degradation due to adhesive layer failure.

[0023] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the nested composite magnet structure in Example 1; Figure 2 This is a schematic diagram of the structure of the multilayer magnet with alternating stacked layers in Example 2; Figure 3 The relationship between magnetic flux loss and time is shown for the nested composite structure magnet of Example 1 and the stacked alternating multilayer structure magnet of Example 2. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0026] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0027] Example 1 A method for preparing nested anisotropic bonded magnets includes: NdFeB powder was mixed with acetone, coupling agent KH570, and bisphenol A epoxy resin E-20 to prepare NdFeB mixed magnetic powder. KH570 accounted for 1‰ of the mass of NdFeB mixed magnetic powder, bisphenol A epoxy resin E-20 accounted for 2.1% of the mass of NdFeB mixed magnetic powder, and acetone accounted for 5% of the mass of NdFeB mixed magnetic powder. SmFeN powder was mixed with acetone, coupling agent KH570, and bisphenol A type epoxy resin E-20 to prepare SmFeN mixed magnetic powder. KH570 accounted for 1‰ of the mass of SmFeN mixed magnetic powder, bisphenol A type epoxy resin E-20 accounted for 2.1% of the mass of SmFeN mixed magnetic powder, and acetone accounted for 5% of the mass of SmFeN mixed magnetic powder. Subsequently, NdFeB mixed magnetic powder and SmFeN mixed magnetic powder were pressed into compacts of different sizes under an orientation magnetic field, with a pressure of 8 tons / cm². 2 The pressing time is 30 seconds, followed by demagnetization. Then, the compact is pressed in a nested arrangement to obtain a structure where SmFeN magnets are nested inside NdFeB magnets (e.g., Figure 1 (as shown); where the mass ratio of NdFeB compact to SmFeN compact is 2:8; the orientation method is to apply a continuous orientation magnetic field to the anisotropic magnetic powder by setting an orientation coil outside the mold, the magnetic field magnitude is 1.8T, the orientation magnetic field duration is 50s, and nested anisotropic bonded magnets are obtained.

[0028] The structure of the nested, anisotropic bonded magnets obtained in this embodiment is as follows: Figure 1 As shown in the figure, the block-shaped SmFeN magnet is nested inside the NdFeB magnet at the center. The SmFeN magnet is arranged in a 3mm×3mm×3mm cube structure, while the NdFeB magnet is arranged in a 5mm×5mm cube structure outside the SmFeN magnet.

[0029] Example 2 A method for preparing a multilayer anisotropic bonded magnet includes: NdFeB powder was mixed with acetone, coupling agent KH570, and bisphenol A epoxy resin E-20 to prepare NdFeB mixed magnetic powder. KH570 accounted for 1‰ of the mass of NdFeB mixed magnetic powder, bisphenol A epoxy resin E-20 accounted for 2.1% of the mass of NdFeB mixed magnetic powder, and acetone accounted for 5% of the mass of NdFeB mixed magnetic powder. SmCo powder was mixed with acetone, coupling agent KH570, and bisphenol A epoxy resin E-20 to prepare SmCo mixed magnetic powder. KH570 accounted for 1‰ of the mass of SmCo mixed magnetic powder, bisphenol A epoxy resin E-20 accounted for 2.1% of the mass of SmCo mixed magnetic powder, and acetone accounted for 5% of the mass of SmCo mixed magnetic powder. 0.9g of NdFeB mixed magnetic powder and 0.9g of SmCo mixed magnetic powder (mass ratio of NdFeB mixed magnetic powder to SmCo mixed magnetic powder is 1:1) were pressed under an orientation magnetic field to obtain a compact, with a pressure of 8 tons / cm². 2 The pressing time is 30 seconds. Finally, the NdFeB and SmCo preforms are arranged and pressed together to obtain anisotropic bonded magnets with alternating layers of NdFeB and SmCo (e.g., Figure 2 As shown in the figure), the orientation method is to apply a continuous orientation magnetic field to the anisotropic magnetic powder, the magnetic field magnitude is 1.8T, the orientation magnetic field duration is 50s, and anisotropic bonded magnet with a multilayer structure is obtained.

[0030] The structure of the multilayer anisotropic bonded magnet prepared in this embodiment is as follows: Figure 2 As shown, its dimensions are 6mm×6mm×8mm. Each layer of SmCo magnet has the same thickness, and each layer of NdFeB magnet has the same thickness. In this embodiment, the anisotropic bonded magnets in the multilayer structure are arranged in an alternating pattern of SmCo magnet, NdFeB magnet, SmCo magnet, NdFeB magnet, SmCo magnet, and NdFeB magnet from bottom to top.

[0031] Example 3 A method for preparing a multilayer anisotropic bonded magnet includes: NdFeB powder was mixed with acetone, coupling agent KH570, and bisphenol A epoxy resin E-20 to prepare NdFeB mixed magnetic powder. KH570 accounted for 1‰ of the mass of NdFeB mixed magnetic powder, bisphenol A epoxy resin E-20 accounted for 2.1% of the mass of NdFeB mixed magnetic powder, and acetone accounted for 5% of the mass of NdFeB mixed magnetic powder. SmCo powder was mixed with acetone, coupling agent KH570, and bisphenol A epoxy resin E-20 to prepare SmCo mixed magnetic powder. KH570 accounted for 1‰ of the mass of SmCo mixed magnetic powder, bisphenol A epoxy resin E-20 accounted for 2.1% of the mass of SmCo mixed magnetic powder, and acetone accounted for 5% of the mass of SmCo mixed magnetic powder. 0.36g of NdFeB mixed magnetic powder and 1.44g of SmCo mixed magnetic powder (mass ratio of NdFeB mixed magnetic powder to SmCo mixed magnetic powder is 2:8) were pressed under an orientation magnetic field to obtain a compact, with a pressure of 8 tons / cm². 2 The pressing time is 30 seconds. Finally, the NdFeB and SmCo preforms are arranged and pressed together to obtain anisotropic bonded magnets with alternating layers of NdFeB and SmCo (e.g., Figure 2 As shown in the figure), the orientation method is to apply a continuous orientation magnetic field to the anisotropic magnetic powder, the magnetic field magnitude is 1.8T, the orientation magnetic field duration is 50s, and anisotropic bonded magnet with a multilayer structure is obtained.

[0032] Example 4 A method for preparing a multilayer anisotropic bonded magnet includes: NdFeB powder was mixed with acetone, coupling agent KH570, and bisphenol A epoxy resin E-20 to prepare NdFeB mixed magnetic powder. KH570 accounted for 1‰ of the mass of NdFeB mixed magnetic powder, bisphenol A epoxy resin E-20 accounted for 2.1% of the mass of NdFeB mixed magnetic powder, and acetone accounted for 5% of the mass of NdFeB mixed magnetic powder. SmCo powder was mixed with acetone, coupling agent KH570, and bisphenol A epoxy resin E-20 to prepare SmCo mixed magnetic powder. KH570 accounted for 1‰ of the mass of SmCo mixed magnetic powder, bisphenol A epoxy resin E-20 accounted for 2.1% of the mass of SmCo mixed magnetic powder, and acetone accounted for 5% of the mass of SmCo mixed magnetic powder. 0.54g of NdFeB mixed magnetic powder and 1.26g of SmCo mixed magnetic powder (mass ratio of NdFeB mixed magnetic powder to SmCo mixed magnetic powder is 3:7) were pressed under an orientation magnetic field to obtain a compact, with a pressure of 8 tons / cm². 2 The pressing time is 30 seconds. Finally, the NdFeB and SmCo preforms are arranged and pressed together to obtain anisotropic bonded magnets with alternating layers of NdFeB and SmCo (e.g., Figure 2 As shown in the figure), the orientation method is to apply a continuous orientation magnetic field to the anisotropic magnetic powder, the magnetic field magnitude is 1.8T, the orientation magnetic field duration is 50s, and anisotropic bonded magnet with a multilayer structure is obtained.

[0033] Example 5 A method for preparing a multilayer anisotropic bonded magnet includes: NdFeB powder was mixed with acetone, coupling agent KH570, and modified epoxy resin to prepare NdFeB mixed magnetic powder. KH570 accounted for 1‰ of the mass of NdFeB mixed magnetic powder, modified epoxy resin accounted for 2.1% of the mass of NdFeB mixed magnetic powder, and acetone accounted for 5% of the mass of NdFeB mixed magnetic powder. SmCo powder was mixed with acetone, coupling agent KH570, and modified epoxy resin to prepare SmCo mixed magnetic powder. KH570 accounted for 1‰ of the mass of SmCo mixed magnetic powder, modified epoxy resin accounted for 2.1% of the mass of SmCo mixed magnetic powder, and acetone accounted for 5% of the mass of SmCo mixed magnetic powder. The preparation method of the modified epoxy resin is as follows: Under nitrogen protection, 100g of bisphenol A type epoxy resin E-20, 12g of 5-carboxybenzotriazole (CBTA), and 20g of xylene were added to a reaction vessel and heated to 80℃ with stirring to dissolve. 0.5g of triethylamine was added as a catalyst, and the temperature was raised to 110℃ and maintained for 4h. After the epoxy value of the system was monitored to be stable, the solvent and small molecule impurities were removed by vacuum distillation to obtain 5-carboxybenzotriazole graft-modified bisphenol A type epoxy resin E-20.

[0034] 0.36g of NdFeB mixed magnetic powder and 1.44g of SmCo mixed magnetic powder were pressed under an orientation magnetic field to obtain a compact, with a pressure of 8 tons / cm². 2The pressing time is 30 seconds. Finally, the NdFeB and SmCo preforms are arranged and pressed together to obtain anisotropic bonded magnets with alternating layers of NdFeB and SmCo (e.g., Figure 2 As shown in the figure), the orientation method is to apply a continuous orientation magnetic field to the anisotropic magnetic powder, the magnetic field magnitude is 1.8T, the orientation magnetic field duration is 50s, and anisotropic bonded magnet with a multilayer structure is obtained.

[0035] The structure of the anisotropic bonded magnet with a multilayer structure prepared in this embodiment is the same as that in Embodiment 2.

[0036] Example 6 A method for preparing a multilayer anisotropic bonded magnet includes: NdFeB powder was mixed with acetone, coupling agent KH570, and modified epoxy resin to prepare NdFeB mixed magnetic powder. KH570 accounted for 1‰ of the mass of NdFeB mixed magnetic powder, modified epoxy resin accounted for 2.1% of the mass of NdFeB mixed magnetic powder, and acetone accounted for 5% of the mass of NdFeB mixed magnetic powder. SmCo powder was mixed with acetone, coupling agent KH570, and modified epoxy resin to prepare SmCo mixed magnetic powder. KH570 accounted for 1‰ of the mass of SmCo mixed magnetic powder, modified epoxy resin accounted for 2.1% of the mass of SmCo mixed magnetic powder, and acetone accounted for 5% of the mass of SmCo mixed magnetic powder. The preparation method of the modified epoxy resin is as follows: Under nitrogen protection, 80g of bisphenol A type epoxy resin E-20, 8g of 5-carboxybenzotriazole (CBTA), and 20g of xylene were added to a reaction vessel and heated to 80℃ with stirring to dissolve. 0.4g of triethylamine was added as a catalyst, and the temperature was raised to 110℃ and maintained for 4h. After the epoxy value of the system was monitored to be stable, the solvent and small molecule impurities were removed by vacuum distillation to obtain 5-carboxybenzotriazole graft-modified bisphenol A type epoxy resin E-20.

[0037] 0.36g of NdFeB mixed magnetic powder and 1.44g of SmCo mixed magnetic powder were pressed under an orientation magnetic field to obtain a compact, with a pressure of 8 tons / cm². 2 The pressing time is 30 seconds. Finally, the NdFeB and SmCo preforms are arranged and pressed together to obtain anisotropic bonded magnets with alternating layers of NdFeB and SmCo (e.g., Figure 2 As shown in the figure), the orientation method is to apply a continuous orientation magnetic field to the anisotropic magnetic powder, the magnetic field magnitude is 1.8T, the orientation magnetic field duration is 50s, and anisotropic bonded magnet with a multilayer structure is obtained.

[0038] The structure of the anisotropic bonded magnet with a multilayer structure prepared in this embodiment is the same as that in Embodiment 2.

[0039] Comparative Example 1 NdFeB powder was mixed with acetone, coupling agent KH570, and bisphenol A epoxy resin E-20 to prepare NdFeB mixed magnetic powder. KH570 accounted for 1‰ of the mass of NdFeB mixed magnetic powder, bisphenol A epoxy resin E-20 accounted for 2.1% of the mass of NdFeB mixed magnetic powder, and acetone accounted for 5% of the mass of NdFeB mixed magnetic powder. SmFeN powder was mixed with acetone, coupling agent KH570, and bisphenol A type epoxy resin E-20 to prepare SmFeN mixed magnetic powder. KH570 accounted for 1‰ of the mass of SmFeN mixed magnetic powder, bisphenol A type epoxy resin E-20 accounted for 2.1% of the mass of SmFeN mixed magnetic powder, and acetone accounted for 5% of the mass of SmCo mixed magnetic powder. Then, the magnetic powders were uniformly mixed at a mass ratio of 2:8 for NdFeB and SmFeN mixed magnetic powders. Subsequently, the mixed magnetic powders were pressed into compacts under an orientation magnetic field at a pressure of 8 tons / cm². 2 The pressing time is 30s, and the orientation method is to apply a continuous orientation magnetic field of 1.8T to the anisotropic magnetic powder through an orientation coil set outside the mold. The orientation magnetic field lasts for 50s, resulting in a mixed bonded magnet of NdFeB and SmFeN.

[0040] Comparative Example 2 NdFeB powder was mixed with acetone, coupling agent KH570, and bisphenol A type epoxy resin E-20 to prepare NdFeB mixed magnetic powder. KH570 accounted for 1‰ of the mass of NdFeB mixed magnetic powder, bisphenol A type epoxy resin E-20 accounted for 2.1% of the mass of NdFeB mixed magnetic powder, and acetone accounted for 5% of the mass of NdFeB mixed magnetic powder. SmCo powder was mixed with acetone, coupling agent KH570, and bisphenol A epoxy resin E-20 to prepare SmCo mixed magnetic powder. KH570 accounted for 1‰ of the mass of SmCo mixed magnetic powder, bisphenol A epoxy resin E-20 accounted for 2.1% of the mass of SmCo mixed magnetic powder, and acetone accounted for 5% of the mass of SmCo mixed magnetic powder. Then, NdFeB mixed magnetic powder and SmCo mixed magnetic powder were uniformly mixed at a mass ratio of 2:8. Subsequently, the mixed magnetic powder was pressed into a 6mm×6mm×8mm blank under an orientation magnetic field with a pressure of 8 tons / cm². 2 The pressing time was 30s, and the orientation method was to apply a continuous orientation magnetic field of 1.8T to the anisotropic magnetic powder through an orientation coil set outside the mold. The orientation magnetic field lasted for 50s, resulting in a mixed bonded magnet of NdFeB and SmCo.

[0041] Comparative Example 3 NdFeB powder was mixed with acetone, coupling agent KH570, and bisphenol A type epoxy resin E-20 to prepare NdFeB mixed magnetic powder. KH570 accounted for 1‰ of the mass of NdFeB mixed magnetic powder, bisphenol A type epoxy resin E-20 accounted for 2.1% of the mass of NdFeB mixed magnetic powder, and acetone accounted for 5% of the mass of NdFeB mixed magnetic powder. SmCo powder was mixed with acetone, coupling agent KH570, and bisphenol A epoxy resin E-20 to prepare SmCo mixed magnetic powder. KH570 accounted for 1‰ of the mass of SmCo mixed magnetic powder, bisphenol A epoxy resin E-20 accounted for 2.1% of the mass of SmCo mixed magnetic powder, and acetone accounted for 5% of the mass of SmCo mixed magnetic powder. Then, NdFeB mixed magnetic powder and SmCo mixed magnetic powder were uniformly mixed at a mass ratio of 3:7. Subsequently, the mixed magnetic powder was pressed into a 6mm×6mm×8mm blank under an orientation magnetic field with a pressure of 8 tons / cm². 2 The pressing time was 30s, and the orientation method was to apply a continuous orientation magnetic field of 1.8T to the anisotropic magnetic powder through an orientation coil set outside the mold. The orientation magnetic field lasted for 50s, resulting in a mixed bonded magnet of NdFeB and SmCo.

[0042] Comparative Example 4 SmCo was mixed with acetone, coupling agent KH570, and bisphenol A epoxy resin E-20 to prepare SmCo mixed magnetic powder. KH570 accounted for 1‰ of the mass of SmCo mixed magnetic powder, bisphenol A epoxy resin E-20 accounted for 2.1% of the mass of SmCo mixed magnetic powder, and acetone accounted for 5% of the mass of SmCo mixed magnetic powder. SmCo mixed magnetic powder was pressed into a 6mm×6mm×8mm compact under an orientation magnetic field, with a pressure of 8 tons / cm². 2 The pressing time is 30s, and the orientation method is to apply a continuous orientation magnetic field of 1.8T to the anisotropic magnetic powder through an orientation coil set outside the mold. The orientation magnetic field lasts for 50s, resulting in SmCo bonded magnets.

[0043] The nested anisotropic bonded magnet prepared in Example 1 has a center surface magnetic height of about 1.6% compared to the bonded magnet of Comparative Example 1 with the same mass ratio.

[0044] Examples 2-4 ( Figure 2 Magnet samples prepared using the same arrangement as those prepared in Comparative Examples 2-4 were stored at a constant temperature of 120℃. The magnetic flux values ​​of the magnets were measured at 0h, 1h, 2h, 5h, and 40h, and the variation of magnetic flux loss with storage time was calculated and obtained. Figure 3 As shown.

[0045] With prolonged high-temperature storage, magnets prepared by both processes showed a trend of gradually increasing magnetic flux loss, indicating that the high-temperature environment has a certain attenuation effect on the magnetic properties of the magnets. Within the same series of magnets, the magnetic flux loss generally increased with the increase of NdFeB magnetic powder content, reflecting the relatively low magnetic stability of NdFeB magnetic powder under high-temperature conditions.

[0046] Further comparison of different powder mixing methods revealed that, under the same NdFeB magnetic powder content, the magnetic flux loss of the multilayer magnets in Examples 3 and 4 (Series B) was significantly lower than that in Comparative Examples 2 and 3 (Series A). This indicates that the multilayer alternating arrangement structure can, to a certain extent, suppress the attenuation of magnetic properties under high-temperature conditions, effectively leveraging the high-temperature resistance advantage of SmCo magnetic powder, thereby significantly improving the overall high-temperature stability of the magnet. Figure 3 The five curves in the figure, from bottom to top, correspond to Comparative Example 4, Example 3, Comparative Example 2, Example 4, and Comparative Example 3, respectively.

[0047] The magnetic flux losses of the multilayer anisotropic bonded magnets prepared in Examples 5 and 6 after 40 hours were 2.5% and 2.6%, respectively, significantly lower than that of Example 3. Specifically, the magnetic flux loss of the SmCo bonded magnet prepared in Comparative Example 4 after 40 hours was 2.5%, the multilayer magnet prepared in Example 3 after 40 hours was 2.65%, the mixed bonded magnet of NdFeB and SmCo prepared in Comparative Example 2 after 40 hours was 2.9%, the multilayer magnet prepared in Example 4 after 40 hours was 3.25%, and the mixed bonded magnet of NdFeB and SmCo prepared in Comparative Example 3 after 40 hours was 3.45%.

[0048] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0049] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. An anisotropic bonded magnet with a composite structure, characterized in that, The anisotropic bonded magnet is a composite structure magnet in which different types of anisotropic magnetic powder are nested after pressing, or a multilayer structure magnet in which different types of anisotropic magnetic powder are alternately arranged between or within layers after pressing.

2. The anisotropic bonded magnet with a composite structure as described in claim 1, characterized in that, The anisotropic magnetic powder includes at least two of NdFeB, SmFeN, SmCo, and MnBi.

3. A method for preparing an anisotropic bonded magnet with a composite structure as described in any one of claims 1-2, characterized in that, include: Different types of anisotropic magnetic powders were mixed with acetone, coupling agent and binder to obtain different types of mixed magnetic powders. Then, the mixed magnetic powders were pressed into blanks of different sizes under an orientation magnetic field and demagnetized. Then, the blanks were pressed in a nested arrangement to obtain nested anisotropic bonded magnets. The orientation method was to apply a continuous orientation magnetic field of 1.5~3.0T to the anisotropic magnetic powder through an orientation coil set outside the mold, and the orientation magnetic field duration was 1~100s.

4. The method for preparing anisotropic bonded magnets with a composite structure as described in claim 3, characterized in that, The anisotropic magnetic powder includes NdFeB and SmFeN, and the nested composite structure magnet is a composite magnet structure in which one type of magnet is nested inside another type of magnet.

5. The method for preparing anisotropic bonded magnets with a composite structure as described in claim 4, characterized in that, The coupling agent is KH570, and the binder is bisphenol A type epoxy resin E-20; the binder accounts for 2% to 4% of the mass of the mixed magnetic powder, the coupling agent accounts for 1‰ to 5‰ of the mass of the mixed magnetic powder, and the acetone accounts for 2% to 10% of the mass of the mixed magnetic powder.

6. The method for preparing anisotropic bonded magnet with a composite structure as described in claim 3, characterized in that, The pressure for pressing the mixed glue magnetic powder into a compact is 2-10 tons / cm 2 , and the pressing time is 10-50 s; the pressing method for pressing the compact into an anisotropic bonded magnet comprises one of cold pressing, warm pressing or isostatic pressing, the pressure is 6-60 tons / cm 2 , and the pressing time is 10-100 s.

7. A method for preparing an anisotropic bonded magnet with a composite structure as described in any one of claims 1-2, characterized in that, include: Different types of anisotropic magnetic powders were mixed with acetone, coupling agent and binder to obtain different types of mixed magnetic powders. Then, they were pressed under an orientation magnetic field to obtain compacts. Finally, the different compacts were arranged and pressed to obtain a multilayer anisotropic bonded magnet. The orientation method was to apply a continuous orientation magnetic field of 1.5~3.0T to the anisotropic magnetic powder for 1~100s.

8. The method for preparing anisotropic bonded magnet with a composite structure as described in claim 7, characterized in that, The multilayer structure magnet is a multilayer structure magnet in which one type of magnet and another type of magnet are arranged alternately between or within layers.

9. The method for preparing anisotropic bonded magnet with a composite structure as described in claim 8, characterized in that, The coupling agent is KH570, and the binder is bisphenol A type epoxy resin E-20; the binder accounts for 2% to 4% of the mass of the mixed magnetic powder, the coupling agent accounts for 1‰ to 5‰ of the mass of the mixed magnetic powder, and the acetone accounts for 2% to 10% of the mass of the mixed magnetic powder.

10. The method for preparing anisotropic bonded magnet with a composite structure as described in claim 7, characterized in that, The pressure of pressing the mixed magnetic powder into a compact is 2~10 tons / cm. 2 The pressing time is 10~50s; the pressing method for anisotropic bonded magnets includes cold pressing, warm pressing or isostatic pressing, with a pressure of 6~60 tons / cm³. 2 The compression time is 10~100s.

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